/*
https://leetcode-cn.com/problems/populating-next-right-pointers-in-each-node/solution/tian-chong-mei-ge-jie-dian-de-xia-yi-ge-you-ce-2-4/
 */
public class Solution116 {

    static class Node {
        public int val;
        public Node left;
        public Node right;
        public Node next;

        public Node() {}

        public Node(int _val) {
            val = _val;
        }

        public Node(int _val, Node _left, Node _right, Node _next) {
            val = _val;
            left = _left;
            right = _right;
            next = _next;
        }
    }

    public Node connect(Node root) {
        if (root==null || root.left==null){
            return root;
        }
        root.left.next=root.right;
        if (root.next!=null){
            root.right.next=root.next.left;
        }
        connect(root.left);
        connect(root.right);
        return root;
    }

    public static void main(String[] args) {
        System.out.println(new Solution116().connect(new Node(1,new Node(2,new Node(4),new Node(5),null),new Node(3,new Node(6),new Node(7),null),null)).left.right.next.val);
    }
}
